Load overload protection circuit and boost circuit

Abstract

The utility model relates to the technical field of circuit protection, and provides a load overload protection circuit and a boost circuit, which comprise a boost module, a main control chip and a protection circuit, the protection circuit comprises a switch module, a power-on detection module, an output feedback module, a switch module, a protection module and a main control chip, and the power-on detection module and the output feedback module which are connected with the protection module are arranged, so that on one hand, the protection module is rapidly controlled by collecting power-on signals of the boosting module; the switch module is further driven to be switched on or switched off; on the other hand, on or off of the movable switch module is controlled based on detection feedback of the output voltage of the boost module; therefore, rapid conduction of the boost module is realized, double trigger processing of undervoltage when the load is overloaded is realized, working safety of the boost module is guaranteed, repeated starting of the circuit is avoided, and the circuit is simple, has few elements and is low in cost.

Description

Technical Field

[0001] The utility model relates to the technical field of circuit protection, in particular to a load overload protection circuit and a boost circuit. Background Technique

[0002] The electric current that can continuously pass through an electrical circuit without overheating the wire is called the safe carrying capacity or safe current. When the load is too large, the current flowing through the wire will exceed the safe carrying capacity, which is wire overload. Wire overload will cause the wire temperature to rise. Generally, the maximum allowable operating temperature of the wire is 65°C. When the wire is overloaded and the wire temperature exceeds the maximum allowable operating temperature, it will cause the wire insulation layer to age rapidly or even cause a fire due to line combustion. Therefore, in the actual power supply circuit, we usually have an overload protection device function to prevent potential safety hazards caused by load overload.

[0003] In order to prevent undervoltage caused by overload in the existing circuit, generally, a voltage dividing resistor is used to detect the output voltage, and then it is fed back to the control end of the boost circuit to output a control signal to turn off the input of the boost circuit, so as to achieve undervoltage protection. This technical solution cannot limit the restart switch when the load overload is not lifted, and there is a problem of repeated startup. Summary of the Invention

[0004] The utility model provides a load overload protection circuit and a boost circuit, which solve the technical problem that the existing load overload protection circuit cannot effectively identify the load state and there is repeated startup.

[0005] To solve the above technical problems, the utility model provides a load overload protection circuit, including a power-on detection module, an output feedback module, a switch module, a protection module and a main control chip; the switch module is connected in series between the input end of the boost module and the power input end; the output end of the protection module is connected to the control end of the switch module, and its input end is connected to the output feedback module and the power-on detection module; the input end of the power-on detection module is connected to the main control chip, and the output end is connected to the control end of the protection module; the main control chip is connected to the internal main circuit of the switch module.

[0006] This basic solution sets a power-on detection module and an output feedback module connected to the protection module. On the one hand, by collecting the power-on signal of the boost module, it can quickly control the protection module, and then drive the switch module to conduct or turn off; on the other hand, based on the detection and feedback of the output voltage of the boost module, it controls the switch module to conduct or turn off; thus realizing the quick conduction of the boost module, and realizing the dual-trigger processing of undervoltage when the load is overloaded, thereby ensuring the working safety of the boost module, avoiding repeated startup of the circuit, and the circuit is simple, with few components and low cost.

[0007] In a further embodiment, the output feedback module includes a first diode ZD1 and a resistor R1. The negative electrode of the first diode ZD1 is connected to the output terminal of the boost module, and the positive electrode is connected to the control terminal of the protection module through the resistor R1.

[0008] Based on the voltage stabilizing diode characteristic of the first diode, when the boost module outputs normally and stably, it replaces the power-on detection module to continuously drive the protection module to control the switch module to conduct, thus ensuring the stable output of the circuit; when the circuit is under-voltage, the first diode is cut off and then drives the protection module to control the switch module to turn off, performing overload protection.

[0009] In a further embodiment, the power-on detection module includes a first capacitor C1, a second diode D2, a resistor R2 and a resistor R3. One end of the first capacitor C1 is connected to the main control chip, and the other end is connected to the control terminal of the protection module through the resistor R2; one end of the resistor R3 is connected to the other end of the first capacitor C1, and the other end is grounded; the positive electrode of the second diode D2 is connected to the control terminal of the protection module, and the negative electrode is connected to the main control chip.

[0010] This solution takes the first capacitor C1 as the core:

[0011] (1) When receiving the high-level signal output by the main control chip, it conducts and starts charging. Since the voltage of the capacitor cannot change suddenly, the first capacitor C1 is equivalent to a short circuit instantaneously at the high level of EN, and then drives the protection module to control the switch module to conduct;

[0012] (2) Design an RC delay circuit composed of the first capacitor C1 and the resistor R3, so that the boost module outputs enough voltage to the output feedback module to maintain the protection module in the conducting state;

[0013] (3) When the circuit is under-voltage, the first capacitor C1 is charged but the voltage on its left side is not enough to maintain the conduction of the protection module, so the switch module is always in the off state, realizing under-voltage self-detection and self-protection;

[0014] (4) Moreover, only when the main control module sets the first capacitor C1 to low (EN is set to low), the first capacitor C1 discharges through R3 to prepare for the next turn-on, thereby avoiding repeated startups caused by unresolved load overload.

[0015] In a further embodiment, the protection module includes a first switching transistor Q1. The control terminal of the first switching transistor Q1 is connected to the output feedback module and the power-on detection module, the first end is connected to the switch module, and the second end is grounded.

[0016] In a further embodiment, the switch module includes a second switching transistor Q2, a resistor R4, and a resistor R5; a first end of the second switching transistor Q2 is connected to an input end of the boost module, a second end is connected to a power input end, and a control end is connected to the protection module through the resistor R4; two ends of the resistor R5 are respectively connected to a second end and a control end of the protection module.

[0017] In a further embodiment, the first switching transistor Q1 is a MOS transistor, and the second switching transistor Q2 is a triode or a MOS transistor.

[0018] This solution uses MOS transistors to construct the switch module, which can adapt to the circuit output of large current, thus ensuring the safety of the circuit.

[0019] In a further embodiment, the first diode ZD1 is a voltage stabilizing diode.

[0020] The present invention provides a boost circuit, including a boost module, a main control chip, and a protection circuit; the protection circuit is a load overload protection circuit as described above, including a switch module, a power-on detection module, an output feedback module, a switch module, a protection module, and a main control chip.

[0021] In a further embodiment, the boost module includes a PFC inductor L1, a third diode D3, and a boost chip U1; one end of the PFC inductor L1 is connected to an output end of the switch module, and the other end is connected to a positive electrode of the third diode D3; an input end of the boost chip U1 is connected to the output end of the switch module and is also connected to the main control chip; a negative electrode of the third diode D3 is connected to a load and is also connected to an input end of the output feedback module.

[0022] This solution wakes up the boost chip U1 and the power-on detection module through the main control chip, and then conducts the output loop of the boost module, and synchronously cooperates with the output feedback module to achieve double under-voltage protection, thereby optimizing the safety of the boost circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a system framework diagram of a boost circuit provided by an embodiment of the present utility model;

[0024] Figure 2 is provided by an embodiment of the present utility model Figure 1 hardware circuit diagram;

[0025] Wherein: boost module 1, main control chip 2, switch module 3, power-on detection module 4, output feedback module 5, protection module 6, load 7. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] The embodiments of the present utility model will be specifically described below in conjunction with the accompanying drawings. The examples are given only for illustrative purposes and should not be construed as limiting the present utility model. The included drawings are for reference and illustration only and do not constitute a limitation to the scope of patent protection of the present utility model, because many changes can be made to the present utility model without departing from its spirit and scope.

[0027] Example 1

[0028] A load overload protection circuit provided by an embodiment of the present utility model is as Figure 1 、 Figure 2 shown. In this embodiment, it includes a power-on detection module 4, an output feedback module 5, a switch module 3, a protection module 6, and a main control chip 2; the switch module 3 is connected in series between the input end of the boost module 1 and the power input end VIN; the output end of the protection module 6 is connected to the control end of the switch module 3, and its input end is connected to the output feedback module 5 and the power-on detection module 4; the input end of the power-on detection module 4 is connected to the main control chip 2, and the output end is connected to the control end of the protection module 6; the main control chip 2 is connected to the internal main circuit of the switch module 3.

[0029] In this embodiment, the output feedback module 5 includes a first diode ZD1 and a resistor R1. The negative electrode of the first diode ZD1 is connected to the output end of the boost module 1, and the positive electrode is connected to the control end of the protection module 6 through the resistor R1.

[0030] In this embodiment, the first diode ZD1 is a voltage-regulating diode.

[0031] Based on the voltage-regulating diode characteristic of the first diode in this embodiment, when the boost module 1 outputs normally and stably, it drives the protection module 6 to control the switch module 3 to conduct continuously instead of the power-on detection module 4, so as to ensure the stable output of the circuit; when the circuit is under-voltage, the first diode is cut off and then drives the protection module 6 to control the switch module 3 to turn off, performing overload protection.

[0032] In this embodiment, the power-on detection module 4 includes a first capacitor C1, a second diode D2, a resistor R2, and a resistor R3. One end of the first capacitor C1 is connected to the main control chip 2, and the other end is connected to the control end of the protection module 6 through the resistor R2; one end of the resistor R3 is connected to the other end of the first capacitor C1, and the other end is grounded; the positive electrode of the second diode D2 is connected to the control end of the protection module 6, and the negative electrode is connected to the main control chip 2.

[0033] Among them, when the lower side of the resistor R2 is overloaded on the left side of the first capacitor C1, the turn-off speed can be accelerated;

[0034] SeeFigure 2 If the left side of the first capacitor C1 is connected to the upper side of R2, after conduction, the Vgs of the first switching transistor Q1 is 2.62V, the output terminal VOUT (i.e., the load 7) is under-voltage, and there is no current in the first diode ZD1. Since the voltage of the capacitor cannot change suddenly, at this time, the first capacitor C1 needs to continue charging through R2 / R3 until the VGS voltage of the second switching transistor Q2 drops low enough to turn off the second switching transistor Q2.

[0035] In this embodiment, the first capacitor C1 is connected to the lower side of the resistor R2. After conduction, the VGS of the second switching transistor Q2 is still 2.62V, but the voltage on the left side of the first capacitor C1 is only 0.24V. When the load 7 is overloaded and under-voltage, there is no current in the first diode ZD1 and no current in the resistor R2 either.

[0036] This embodiment takes the first capacitor C1 as the core:

[0037] (1) When receiving the high-level signal output by the main control chip 2, it conducts and starts charging. Since the voltage of the capacitor cannot change suddenly, the first capacitor C1 is equivalent to a short circuit instantaneously when EN is at a high level, and then drives the protection module 6 to control the switch module 3 to conduct;

[0038] (2) Design the first capacitor C1 and the resistor R3 to form an RC delay circuit, so that the boost module 1 outputs enough voltage to the output feedback module 5 normally to maintain the protection module 6 in a conducting state;

[0039] (3) When the circuit is under-voltage, the first capacitor C1 charges, but the voltage on its left side is not enough to maintain the conduction of the protection module 6. Therefore, the switch module 3 is always in an off state, realizing under-voltage self-detection and self-protection;

[0040] (4) Moreover, only when the main control module sets the first capacitor C1 to low (EN is set to low), the first capacitor C1 discharges through R3 to prepare for the next turn-on, thereby avoiding repeated startups caused by the unresolved overload of the load 7.

[0041] In this embodiment, the protection module 6 includes a first switching transistor Q1. The control end of the first switching transistor Q1 is connected to the output feedback module 5 and the power-on detection module 4, the first end is connected to the switch module 3, and the second end is grounded.

[0042] In this embodiment, the first switching transistor Q1 is a MOS transistor or a triode.

[0043] In this embodiment, the switch module 3 includes a second switching transistor Q2, a resistor R4, and a resistor R5; the first end of the second switching transistor Q2 is connected to the input end of the boost module 1, the second end is connected to the power input terminal VIN, and the control end is connected to the protection module 6 through the resistor R4; both ends of the resistor R5 are respectively connected to the second end and the control end of the protection module 6.

[0044] In this embodiment, the second switching transistor Q2 is a MOS transistor.

[0045] In this embodiment, a MOS transistor is used to construct the switching module 3, which can adapt to the circuit output with large current, thus ensuring the safety of the circuit.

[0046] Example 2

[0047] The present invention provides a boost circuit. Refer to Figure 1 , Figure 2 , which includes a boost module 1, a main control chip 2 and a protection circuit; the protection circuit is a load overload protection circuit as described above, including a switching module 3, a power-on detection module 4, an output feedback module 5, a switching module 3, a protection module 6 and a main control chip 2.

[0048] In this embodiment, the boost module 1 includes a PFC inductor L1, a third diode D3 and a boost chip U1; one end of the PFC inductor L1 is connected to the output end of the switching module 3, and the other end is connected to the positive electrode of the third diode D3; the input end of the boost chip U1 is connected to the output end of the switching module 3, and it is also connected to the enable end (i.e., pin EN) of the main control chip 2; the negative electrode of the third diode D3 is connected to the load 7 and is also connected to the input end of the output feedback module 5.

[0049] Among them, the boost module 1 is a conventional circuit structure in the art, and will not be elaborated in this embodiment.

[0050] In this embodiment, the main control chip 2 wakes up the boost chip U1 and the power-on detection module 4, and then conducts the output loop of the boost module 1. Synchronously cooperating with the output feedback module 5, double under-voltage protection is realized, and the safety of the boost circuit is optimized.

[0051] Taking the first switching transistor Q1 as an N-channel MOS transistor and the second switching transistor Q2 as a P-channel MOS transistor as an example, the working principle of the load overload protection in this embodiment is as follows:

[0052] First, when the main control chip 2 is powered on, it outputs a high level through pin EN to wake up the boost chip U1; it also outputs a high level through pin EN3.3V, the second diode D2 is reversely cut off, and the first capacitor C1 is conducted and starts to charge. Since the voltage of the capacitor cannot change suddenly, the first capacitor C1 is equivalent to a short circuit at the moment of the EN high level, and the first switching transistor Q1 is conducted.

[0053] After the first switching transistor Q1 is turned on, through the voltage division of resistors R4 and R5, the second switching transistor Q2 is also turned on, and the boost module 1 operates. When the output voltage of the output terminal VOUT exceeds the breakdown voltage of the first diode ZD1, the first diode ZD1 is turned on. The output voltage of the output terminal VOUT minus the breakdown voltage of the first diode ZD1, and the remaining driving voltage is applied to the resistors R1 / R2 / R3 for voltage division to keep the first switching transistor Q1 conducting.

[0054] During the enabling stage of the pin EN3.3V, the first capacitor C1 is charged through the resistor R3. After the enabling is completed, the first capacitor C1 is approximately equal to the voltage of the pin EN3.3V. At this time, removing the EN3.3V signal does not affect the conduction of the first switching transistor Q1.

[0055] After enabling, the output terminal VOUT outputs normally. When the load 7 is overloaded, the output voltage of the output terminal VOUT drops. The voltage division of the output voltage of the output terminal VOUT on the resistors R1 / R2 / R3 is not sufficient to keep the first switching transistor Q1 conducting. The first switching transistor Q1 is turned off, and the second switching transistor Q2 is also turned off to cut off the power supply to the subsequent circuit and the load 7.

[0056] At the same time, the pin EN3.3V is still at a high level. Since the voltage is all applied across the two ends of the first capacitor C1, the first switching transistor Q1 remains off. It is necessary to set the pin EN3.3V to a low level to discharge the first capacitor C1 before the pin EN3.3V can be set to a high level again to turn on the first switching transistor Q1, thereby effectively avoiding repeated startups.

[0057] II. When the overload of the load 7 is not lifted, the enabling of the pin EN3.3V is ineffective, and the output terminal VOUT has no output.

[0058] At this time, when the pin EN3.3V is set to a high level, since the output voltage of the output terminal VOUT cannot rise high enough to keep the first switching transistor Q1 conducting, when the left - hand - side voltage of the first capacitor C1 is charged to a level that is not sufficient to keep the first switching transistor Q1 conducting, the first switching transistor Q1 is turned off, and the second switching transistor Q2 is turned off for input.

[0059] III. EN turn - off process

[0060] Setting the pin EN3.3V to a low level clamps the Vgs voltage of the first switching transistor Q1 through the second diode D2, turning off the first switching transistor Q1, and the first switching transistor Q1 turns off to cut off the input.

[0061] In the embodiment of the present utility model, a power-on detection module 4 and an output feedback module 5 connected to the protection module 6 are provided. On the one hand, by collecting the power-on signal of the boost module 1, the protection module 6 can be quickly controlled, and then the switch module 3 can be driven to conduct or turn off. On the other hand, based on the detection and feedback of the output voltage of the boost module 1, the dynamic switch module 3 is controlled to conduct or turn off. Thus, the boost module 1 can be quickly turned on, and the double-trigger processing of undervoltage when the load 7 is overloaded can be realized, thereby ensuring the working safety of the boost module 1, avoiding repeated startup of the circuit, and the circuit is simple, with few components and low cost.

[0062] The above embodiments are the preferred embodiments of the present utility model, but the embodiments of the present utility model are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present utility model shall be equivalent replacement methods and shall be included in the protection scope of the present utility model.

Claims

1. A load overload protection circuit, characterized in that: It includes a power-on detection module, an output feedback module, a switch module, a protection module and a main control chip; the switch module is connected in series between the input end of the boost module and the input end of the power supply; the output end of the protection module is connected to the control end of the switch module, and its input end is connected to the output feedback module and the power-on detection module; the input end of the power-on detection module is connected to the main control chip, and the output end is connected to the control end of the protection module; the main control chip is also connected to the main circuit inside the switch module.

2. A load overload protection circuit as claimed in claim 1, characterized in that: The output feedback module includes a first diode ZD1 and a resistor R1. The cathode of the first diode ZD1 is connected to the output end of the boost module, and the anode of the first diode ZD1 is connected to the control end of the protection module through the resistor R1.

3. A load overload protection circuit as claimed in claim 2, characterized in that: The power-on detection module includes a first capacitor C1, a second diode D2, a resistor R2 and a resistor R3, one end of the first capacitor C1 is connected to the main control chip, and the other end is connected to the control end of the protection module through the resistor R2; one end of the resistor R3 is connected to the other end of the first capacitor C1, and the other end is grounded; the positive electrode of the second diode D2 is connected to the control end of the protection module, and the negative electrode is connected to the main control chip.

4. A load overload protection circuit as claimed in claim 3, characterized in that: The protection module includes a first switch tube Q1 , a control end of the first switch tube Q1 is connected to the output feedback module and the power-on detection module, a first end is connected to the switch module, and a second end is grounded.

5. A load overload protection circuit as claimed in claim 4, characterized in that: The switch module includes a second switch tube Q2, a resistor R4 and a resistor R5; the first end of the second switch tube Q2 is connected to the input end of the boost module, the second end is connected to the power input end, and the control end is connected to the protection module through the resistor R4; the two ends of the resistor R5 are respectively connected to the second end and the control end of the protection module.

6. A load overload protection circuit as claimed in claim 5, characterized in that: The first switch tube Q1 is a triode or a MOS tube, and the second switch tube Q2 is a MOS tube.

7. A load overload protection circuit as claimed in claim 2, characterized in that: The first diode ZD1 is a voltage stabilizing diode.

8. A boost circuit, characterized in that: It includes a boost module, a main control chip and a protection circuit; the protection circuit is a load overload protection circuit as described in any one of claims 1 to 7, including a switch module, a power-on detection module, an output feedback module, a switch module, a protection module and a main control chip.

9. A boost circuit as claimed in claim 8, characterized in that: The boost module includes a PFC inductor L1, a third diode D3 and a boost chip U1; one end of the PFC inductor L1 is connected to the output end of the switch module, and the other end is connected to the positive electrode of the third diode D3; the input end of the boost chip U1 is connected to the output end of the switch module and is also connected to the main control chip; the cathode of the third diode D3 is connected to the load and is also connected to the input end of the output feedback module.

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